75 research outputs found
Synthesis And Characterization Of Astaxanthin- Metal Ions (Cu2+ And Zn2+) Complex
No full textVol. 14 | No. 2 |877-886| April - June | 2021
ISSN: 0974-1496 | e-ISSN: 0976-0083 | CODEN: RJCABP
http://www.rasayanjournal.com
http://www.rasayanjournal.co.in
Rasayan J. Chem., 14(2), 877-886(2021)
http://dx.doi.org/10.31788/ RJC.2021.1426209 This work is licensed under a CC BY 4.0 license.
SYNTHESIS AND CHARACTERIZATION OF ASTAXANTHIN-
METAL IONS (Cu2+ and Zn2+) COMPLEX
S. Wibowo1,, B. D. Prakoso1, S. Najihah1, Z. H. Fajar1, S. Widyarti1,
A. Sabarudin2, D. W. Soeatmadji3 and S. B. Sumitro1
1Department of Biology, Faculty of Mathematics and Natural Sciences, Brawijaya University Jl.
Veteran, Malang 65145, East Java, Indonesia.
2Department of Chemistry, Faculty of Mathematics and Natural Sciences, Brawijaya University,
Jl. Veteran, Malang 65145, East Java, Indonesia.
3Department of Internal, School of Medicine, Brawijaya University, Jl. Veteran, Malang 65145,
East Java, Indonesia.
Corresponding Author: [email protected]
ABSTRACT
This study aimed was to determine the optimal ratio, duration, and temperature reaction to form the astaxanthin-
metal ions complex based on the UV-Vis spectrum profile and confirmation of complex formation using FTIR. The
method used consists of the synthesis of the astaxanthin-metal ions (Cu2+ and Zn2+) and the determination of
complex formation based on the UV-Vis spectrum profile which is evaluated at a wavelength of 190–790 nm. Then
the selected complexes were analyzed for their functional groups using FTIR at wavenumbers of 400-4000 cm-1.
Astaxanthin-metal ions complex was successfully synthesized and characterized by UV-Vis and FTIR. The optimal
ratio, temperature, and stirrer time for astaxanthin-Cu2+ are (3:1), 78oC, and 5 minutes, while astaxanthin-Zn2+ is
(1:1), 78oC, and 15 minutes, respectively
Cholesterol-dependent cytolysins.
No full textThe cholesterol-dependent cytolysins (CDCs) are part of a large family of pore-forming proteins that include the human proteins perforin and the complement membrane attack complex. The activity of all family members is focused on membranes, but the proteins are themselves involved in a diverse range of phenomena. An overview of some of these phenomena is provided here, along with an historical perspective of CDCs themselves and how our understanding of their mechanism of action has developed over the years. The way in which pore formation depends on specific characteristics of the membrane under attack as well as of the protein doing the attacking is emphasised. The cholesterol-dependent cytolysins (CDCs) have been the focus of a renewed keen research interest for over ten years now. Their importance has been even further enhanced by the homology now identified between them and the membrane attack complex/perforin (MACPF) family of proteins, which includes several components of the complement cascade as well as perforin itself. In this chapter I aim to provide an overview of our understanding of the interaction between CDCs and other members of what is now called the MACPF/CDC superfamily, with their target membranes. CDCs (also in the past known as thiol-activated toxins or cholesterol-binding toxins) were originally identified from four Gram-positive bacterial genera (Clostridium, Listeria, Bacillus and Streptococcus). Well-known examples include listeriolysin, perfringolysin, streptolysin and pneumoysin. Listeriolysin from L. monocytogenes is responsible for the escape of bacteria from the phagosome to colonise the cytoplasm and has been applied as a protein adjuvant in the development of vaccines against cancer and tuberculosis, for example. Perfringolysin from C. perfringens (Fig. 1A) has become perhaps the most studied CDC4 and has an important role in pathology associated with infection (gangrene). Streptolysin from S. pyogenes is another intensely studied CDC and has been applied widely in experimental permeabilisation of biological membranes. Pneumolysin is a major virulence determinant for S. pneumoniae, allowing bacterial invasion of tissues and mediating inflammation and the activation of the complement cascade. However, CDCs have now, for example, been identified in the bacteria Arcanobacterium pyogenes and Gardnerella vaginalis and there also appear to be homologues outside prokaryotes such as the sea anemone Metridium senile pore-forming toxin metridiolysin. The homology with the MACPF family was unknown until the first structures of the canonical fold of that family were solved, revealing the now characteristic MACPF/CDC fold of a twisted 3-sheet around which helices are clustered (Fig. 1A and D). Without any significant other sequence homology, the fold of this superfamily of pore-forming and membrane-binding proteins has been conserved by compensatory mutation around a handful of key conserved glycines. The glycines presumably act as critical hinges during the dramatic refolding that CDCs are known to undergo and which is presumably the selective advantage of this specific structure that has caused it to be conserved over such a vast evolutionary timescale. While not all MACPF domains are involved in pore formation-for example, C6 and C8beta--they are all apparently involved in action on membranes. The dramatic refolding undergone by CDCs is tightly coupled to their oligomerisation and results in the conversion of the helices hemming the core 3-sheet of the MACPF/CDC domain into a pair of beta-hairpins which in tandem and alongside those from other subunits within the oligomer insert into the membrane to create a pore (Fig. 1A-C). It is obviously the basic assumption that where nonCDC members of the superfamily-such as complement proteins and perforin-act on membranes they do so by a mechanism involving similar refolding.58 Even where a member of the MACPF/CDC superfamily is not known to form a pore, or has been shown not to-at least alone-the same conformational change could have other adaptive functions during activity on or at membranes. However, the bicomponent nature of some pore-forming toxins alerts us that showing an absence of activity for one pure protein does not mean that they do not contribute to pore formation quite directly, since that may require the presence of another MACPF/CDC family member or members from the same specific system. Complement acts by a combination of the C5b-8 complex of proteins preassembled on a target membrane recruiting C9 to form a lesion, which may be a complete ring of C9 associated with the C5b-8 or an arc-electron microscopy images show both possibilities.Perforin acts in concert with granzymes, to trigger apoptosis when delivered by cytotoxic cells at their targets (damaged, transformed and infected host cells). Incomplete rings are visible for perforin also and there are many unresolved issues concerning its mechanism and the dependence ofgranzymes on it for their delivery
Pore-forming toxins.
No full textPore-forming toxins are widely distributed proteins which form lesions in biological membranes. In this review, bacterial pore-forming toxins are treated as a paradigm and discussed in terms of the structural principles on which they work. Then, a large family of bacterial toxins, the cholesterol-binding toxins, are analyzed in depth to provide an overview of the processes involved in pore formation. The ways in which the cholesterol-binding toxins (cholesterol-dependent cytolysins) interact with membranes and form pores, the structure of the monomeric soluble and oligomeric pore-forming states, and the effects of the toxin on membrane structure are discussed. By surveying the range of work which has been done on cholesterol-binding toxins, a working model is elaborated which reconciles two current, apparently diametrically opposed, models for their mechanism
Neutron scattering: good news for biotechnology
No full textIn its application-to biological systems, neutron scattering is still an emerging technology with a great deal of potential. A consequence of the native interaction between neutrons and biological samples is that the hydrogen isotopes 1H and 2H are most significant in dynamical and structural studies, respectively
Inactivation and activity of cholesterol-dependent cytolysins: what structural studies tell us.
No full textThe homologous bacterially expressed cholesterol-dependent cytolysins (CDCs) form pores via oligomerization; this must occur preferentially once the target membrane has been engaged. Conformational changes in CDCs then drive partition from an aqueous environment to a lipidic one. This review addresses how premature oligomerization is prevented, how conformational changes are triggered, and how cooperativity between subunits brings about new functionality absent from isolated protomers. Variations are found in the answers provided by the CDCs to these issues. Some toxins use pH as a trigger of activity, but recent results have shown that dimerization in solution is an alternative way of preventing premature oligomerization, in particular for the CDC from Clostridium perfringens, perfringolysin. More controversially, there is still no resolution to the debate as to whether incomplete (arciform) oligomers form pores: recent results again suggest that they do
Characterization and Epidemiology of Viruses Belonging to the African Haemorrhagic Fever group, with Particular Reference to Marburg.
No full textBetween July and September 1976, widespread interest on an international scale was directed towards outbreaks of viral haemorrhagic fever which occurred in the southern Sudan and northern Zaire. This thesis is an account of the work carried out by the author with the assistance of three members of the staff of the Special Pathogens Unit at the Microbiological Research Establishment, Porton Down, Salisbxiry. It describes the successful isolation and identification of the aetiologic agent, and also describes the successful transmission of the disease to guinea pigs and monkeys. Characteristic pathological lesions were found in all the experimental animals. The agent produced characteristic intracytoplasmic inclusion bodies in tissue culture which could be detected by both conventional staining and by immunofluorescent techniques. Studies have shown that the agent although morphologically identical to Marburg virus, was antigenically distinct. In concurrence with other principle investigators, the name Ebola virus was proposed. The disease induced in monkeys by infection with Ebola virus was very similar to that which occurs in man. Rhesus and Vervet monkeys therefore seem to be suitable experimental animals in which to study the pathogenesis of the disease and also to evaluate the various aspects of therapy. Infection with the Sudanese strain of the virus appeared to be less virulent in both guinea pigs and monkeys compared with that of the Zaire strain. Rneous monkeys were treated with human leucocyte interferon prophylactics!ly and after experimental infection with the Zaire strain of Ebola virus. Viraemia was delayed and clinically survival appeared to be enhanced. There was no consistent difference in the pathological changes or the outcome ol the infection between the treated and the untreated animals. Epidemiological studies carried out on material from the Sudan, showed antibodies to Ebola virus which were detected by immunofluorescence in 42 of 48 patients in Maridi who had been diagnosed clinically, but only in 6 of 31 patients in Nzara. The possibility of the indirect irnmunofluorescent test not being sufficiently sensitive is discussed. Of Maridi case contacts in hospital and in the local community only 19% had antibodies. Very few of them gave any history of illness indicating that Ebola virus can cause a mild disease or even sub-clinical infection. Detailed virological investigations were carried out on a patient infected with Ebola virus
RNA pseudoknots and the regulation of protein synthesis.
No full textRNA pseudoknots are structural elements found in almost all classes of RNA. Pseudoknots form when a single-stranded region in the loop of a hairpin base-pairs with a stretch of complementary nucleotides elsewhere in the RNA chain. This simple folding strategy is capable of generating a large number of stable three-dimensional folds that display a diverse range of highly specific functions in a variety of biological processes. The present review focuses on pseudoknots that act in the regulation of protein synthesis using cellular and viral examples to illustrate their versatility. Emphasis is placed on structurally well-defined pseudoknots that play a role in internal ribosome entry, autoregulation of initiation, ribosomal frameshifting during elongation and trans-translation
Ribosomal acrobatics in post-transcriptional control.
No full textHigh-resolution structures have given an extremely detailed view of aspects of ribosomes, including some near-functional states. Here, we review the importance of cryo-electron microscopy, among other techniques, in giving an understanding of the higher dynamics of the ribosome accompanying active recruitment of mRNA to the small subunit and translocation of tRNAs. Recent data show that careful use of a variety of different techniques is necessary for a proper understanding of the basis of function in systems such as the ribosome
Assessing the accuracy of predictive models with interval-censored data
No full textThis is a pre-copyedited, author-produced PDF of an article accepted for publication in Biostatistics following peer review. The version records “Wu Y and Cook RJ (2022), Assessing the accuracy of predictive models with interval-censored data, Biostatistics, 23 (1): 18–33”. DOI: 10.1093/biostatistics/kxaa011 is available online at: https://doi.org/10.1093/biostatistics/kxaa011.We develop methods for assessing the predictive accuracy of a given event time model when the validation sample is comprised of case K interval-censored data. An imputation-based, an inverse probability weighted (IPW), and an augmented inverse probability weighted (AIPW) estimator are developed and evaluated for the mean prediction error and the area under the receiver operating characteristic curve when the goal is to predict event status at a landmark time. The weights used for the IPW and AIPW estimators are obtained by fitting a multistate model which jointly considers the event process, the recurrent assessment process, and loss to follow-up. We empirically investigate the performance of the proposed methods and illustrate their application in the context of a motivating rheumatology study in which human leukocyte antigen markers are used to predict disease progression status in patients with psoriatic arthritis.National Natural Science Foundation of China, Grant 11701295 (to YW) ||
Discovery Grants from the Natural Science and Engineering Research Council of Canada, RGPIN 155849 (to RJC) ||
Canadian Institutes of Health Research, FRN 13887 (to RJC
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